JOURNAL HOME CME HOME THIS MONTH PAST ISSUES ETOC COLLECTIONS AUTHORS REVIEWERS EDITORIAL BOARD FEEDBACK RSS HELP
		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a colleague Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via ISI Web of Science (1) Citing Articles via Google Scholar Google Scholar Articles by Greif, R. Articles by Sessler, D. I. Search for Related Content PubMed PubMed Citation Articles by Greif, R. Articles by Sessler, D. I. Related Collections Postanesthetic Care Unit Monitoring (Non-cardiac)

---

GENERAL ARTICLES

The Threshold and Gain of Thermoregulatory Vasoconstriction Differs During Anesthesia in the Dependent and Upper Arms in the Lateral Position

Robert Greif, MD^*, Sonja Laciny, MD, Angela Rajek, MD, Anthony G. Doufas, MD, PhD, and Daniel I. Sessler, MD^||

*Department of Anesthesiology and Intensive Care Medicine, Donauspital/SMZO; Private practice, Vienna, Austria; Department of Cardiothoracic and Vascular Anesthesia, University of Vienna, Austria; Department of Anesthesiology, University of Louisville, Kentucky; and OUTCOMES RESEARCH^TM Institute, Louisville, Kentucky, and ||Ludwig Boltzmann Institute, University of Vienna, Austria

Address correspondence and reprint requests to Daniel I. Sessler, MD, Outcomes Research Institute, 501 E. Broadway Ave., Louisville, KY 40202. Address e-mail to sessler{at}louisville.edu

Increased intraluminal pressure may help maintain vasodilation in a dependent arm even after hypothermia triggers centrally mediated thermoregulatory vasoconstriction. We therefore tested the hypotheses that the threshold (triggering core temperature) and gain (increase in vasoconstriction per degree centigrade) of cold-induced vasoconstriction is reduced in the dependent arm during anesthesia. Anesthesia was maintained with 0.4 minimum alveolar anesthetic concentration of desflurane in 10 volunteers in the left-lateral position. Mean skin temperature was reduced to 31°C to decrease core body temperature. Fingertip blood flow in both arms was measured, as was core body temperature.The vasoconstriction threshold was slightly, but significantly, less in the dependent arm (36.2°C ± 0.3°C, mean ± SD) than in the upper arm (36.5°C ± 0.3°C). However, the gain of vasoconstriction in the dependent arm was 2.3-fold greater than in the upper arm. Consequently, intense vasoconstriction (i.e., a fingertip blood flow of 0.15 mL/min) occurred at similar core temperatures. In the lateral position, the vasoconstriction threshold was reduced in the dependent arm; however, gain was also increased in the dependent arm. The thermoregulatory system may thus recognize that hydrostatic forces reduce the vasoconstriction threshold and may compensate by sufficiently augmenting gain.

IMPLICATIONS: The threshold for cold-induced vasoconstriction is reduced in the dependent arm, but the gain of vasoconstriction is increased. Consequently, the core temperature triggering intense vasoconstriction was similar in each arm, suggesting that the thermoregulatory system compensates for the hydrostatic effects of the lateral position.

Anesthesia & Analgesia® is published for the International Anesthesia Research Society® by Lippincott Williams & Wilkins with the assistance of Stanford University Libraries' HighWire Press®. Copyright 2006 by the International Anesthesia Research Society. Online ISSN: 1526-7598   Print ISSN: 0003-2999